South Australian Premier Jay Weatherill has conceded that job losses at Holden's Elizabeth plant are likely even after a multi-million dollar sum is paid to parent company General Motors.

Mr Weatherill recently travelled to the United States to meet with GM executives at the company's headquarters in Detroit.

During the trip, he announced that the State and Federal Governments would pay a "substantial amount" to GM to keep its factories in Australia.

Mr Weatherill has not said how much will be paid, but one workforce analyst has estimated $200 million will be needed to satisfy the company.

After returning to Adelaide on Tuesday, Mr Weatherill admitted that the local car industry will probably be downsized even after the money is paid.

"I think that's likely but what we want to do is minimise the reduction in the number of jobs in South Australia and to create a secure platform from which we can grow," he said.

"I don't think there's any doubt that what we are talking about here is potentially a smaller car industry in Australia. What we want it to be is a secure car industry."

The Elizabeth car assembly plant employs 2500 people.

Commodore future

The Premier also indicated that the Commodore may no longer be the manufacturing centrepiece of the Elizabeth plant.

Mr Weatherill says the local industry will focus more on producing parts for models made elsewhere.

"I think we should still be making cars but I also think that we should have a secure place in General Motors' global plan for making cars rather than just be a unique provider of cars for the Australian domestic market," he said.

"To have a secure place in the global plans for Holden both the manufacturing of vehicles but also for the components supply chain.

"What's secure is to be part of a global platform where General Motors see the South Australian operation as having some value that respects the capabilities and skills that we have here.

"There are certain capabilities that exist within Australia that don't exist in General Motors generally like rear-wheel drive capability does not exist within the US.

"That's something that could be a particular Australian area of manufacturing and design expertise that means we are part of Holden's global network for the whole of their operations, not just a unique South Australian or Australian car."

'Fear campaign'

Meanwhile, Federal Liberal MP Jamie Briggs has suggested the effects of a Holden closure would not be as bad as some have claimed.

Mr Briggs says the closure of Mitsubishi at Tonsley Park did not result in the southern suburbs falling into ruin.

He says a Federal assistance package would not be a worthwhile investment.

"This is a great big fear campaign by a multi-national company. If you're a small business in SA and you're going through tough times, and there are many, the Government's not there to write a big cheque for you," he said.

"But if you're a multi-national car company who gets to threaten the economy so-called and say this is going to be Armageddon you get a big whopping multi-million-dollar cheque."

'No details'

The State Opposition has withheld support for the assistance package.

Manufacturing spokesman Steven Marshall says he first wants to see the details of the plan before making a decision.

"We're not against a subsidy as long as it's to drive innovation and [research and development] and competitive advantage," he said.

"The simple fact of the matter is we have had no information whatsoever, so it's completely wrong for the Government to come out and say that the Liberals aren't supporting this. We've seen no detail.'

He says the carbon tax is partly to blame for the car industry's current plight.

But Manufacturing Minister Tom Koutsantonis says the Opposition should support any measures that keep the Elizabeth plant in business.

"All I'm asking from them is to go back to November 2011, three short months ago, and support the policy that they had then. A bi-partisan approach to making sure that Holden remains in South Australia," he said.

"General Motors are under a lot of pressure to move their operation off-shore where labour is cheaper."

It's a fundamental human yearning to be a part of something bigger than one's self, and maybe that's what drove my mate Ash to die, far from home, in a bloody foreign war against Islamic State, writes C August Elliott.